Push-pull electron tube for instruments or television



June 26, 1951 Filed Jan. 17, 1950 J. W. ACOSTA PUSH-PULL ELECTRON TUBEFOR INSTRUMENTS OR TELEVISION 2 Sheet s-Sheet 1 Hoe. Sue-5P GENEKITQKV1050 SIGNAL l l I INVENTOR J. W. ACOSTA PUSH-PULL; ELECTRON TUBE FORINSTRUMENTS 0R TELEVISION June 26, 1951 2 Sheets-Sheet 2 Filed Jan. 17,1950 INVENTOR 7'4,

JOJ'E' 072mm W ATTORNEY6.

Patented June 26, 1951 PUSH-PULL ELECTRON TUBE .FOR INSTRU- MENTS ORTELEVISION Jos W. Acosta, Chicago, Ill.

Application January 17, 1950, Serial No. 139,069

8 Claims. 1

This invention relates to cathode ray tubes, tan]? more particularly toa cathode ray picture A main object of the invention is to provide anovel and improved cathode ray tube wherein there is improved control ofthe scanning beams, and wherein distortion is minimized, said tube beingrelatively simple in construction, providing a relatively flat viewingscreen, and being relatively short in length from the front to the rearof the tube.

A further object of the invention is to provide an improved multiple-guncathode ray tube which involves relatively simple components, has arelatively flat screen of substantial size, and which providessubstantially constant brightness for a given degree of modulation ofthe cathode ray beams over all areas of the viewing screen.

Further objects and advantages of the invention will become apparentfrom the following description and claims, and from the accompanyingdrawings, wherein:

Figure 1 is a front elevational view of an improved dual-gun cathode raytube constructed in accordance with the present invention;

Figure 2 is a longitudinal, vertical, cross-sectional view taken throughthe tube of Figure l, and showing a projection lens system which may beemployed with said tube;

Figure 3 is a fragmentary, longitudinal, vertical, cross-sectional viewtaken through a tube according to the present invention, showingschematically the wiring connections to the elements of the tube;

Figure 4 is a view similar to Figure 3, but showing a tube according tothe present invention employing electromagnetic deflection rather thanelectrostatic deflection;

Figure 5 is a vertical, longitudinal, crosssectional view taken througha tube according to the present invention, wherein electrostaticdeflection of the scanning beam is employed at one of the electron gunsof the tube, and electromagnetic deflection of the scanning beam isemployed at the other electron gun of the tube;

Figure 6 is an elevational view of an improved cathode ray tubeaccording to the present invention, showing the use of acceleratingcoils for attracting the electron beams toward the fluorescent viewingscreen, said tube also being provided with projection lens elements forprojecting images.

Referring to the drawings, and more particularly to Figureslto 3,illustrating one form of.

the invention, I I designates the transparent glass envelope of thetube, said envelope comprising a central, enlarged portion l2 andsymmetrical, inclined neck portions l3 and I4 communicating with thecentral portion l2 and directed toward the inner surface of thesubstantially flat, front wall [5 of said central portion. Said innersurface is provided with the conventional coating ll of fluorescentmaterial employed as the screen material of television picture tubes.Designated at l 6 is an inner, conductive coating surrounding thefluorescent screen I! and having an outwardly extending terminal l8which is connected to the positive terminal of a high voltage D. C.power supply, not shown. The coating l6 constitutes the second anode ofthe tube.

Each of the neck portions l3 and I4 contains a conventional electrongun. Thus, as shown in Figures 2 and 3, the electron gun in neck portion13 comprises the heater filament N3, the cathode 2B, the electronmodulating grid 21, the screen grid 22, the focusing ring 23, thehorizontal deflection plates 24 and 25, and the vertical deflectionplates 25 and Bl. As shown in Figure 2, the electron gun in neck portionIt comprises the corresponding elements 19, 20, 2!, 22', 23', 24', 25,26 and 21'.

Secured to the inside surface of the rear wall 28 opposite screen ll andsubstantially equal in diameter thereto is a flat, annular conductivering 28 having an outwardly extending terminal 30 connected to thenegative terminal of a voltage source 32 which is substantially greaterthan the grid-biasing voltage employed with either elec-' tron gun, i.'e., substantially greater than the voltage of the biasing source shownat 31 in Figure 3. The positive terminal of the biasing source 32 isgrounded.

Secured to the rear wall 28 of central portion I2 is a lens 33 which iscooperatively arranged with respect to another lens 34, or a suitablelens system, not shown, to project the picture traced on the fluorescentscreen I! by the electron beams of the respective electron guns onto a.suitable external screen. Since the picture is generated on the screenll, light rays may pass through the transparent wall 28 to theprojection lens system. The picture may be also directly viewed throughthe tranparent front wall l5 of the tube.

Referring to Figure 3, it will be seen that the various elements of therespective electron guns are connected in parallel to suitableelectrical circuits of the type customarily employed in televisionreceivers of the electrostatic deflection type, except that the top,left, horizontal deflection plate 24, as viewed in Figure 3, isconnected to the lower, right, horizontal deflection plate 25, theplates 24 and 25' being connected to one output terminal of thehorizontal sweep generator 35, and the lower, left, horizontaldeflection plate 25 is connected to the upper, right, horizontaldeflection plate 24, the plates 25 and 2 3 being connected to theremaining output terminal of the horizontal sweep generator.

Assuming that the electron beams of both electron guns are focused tostrike a common point on the screen ii, the two beams will be swept intandem synchronously over the screen, and since the modulating grids 2!and El are connected together, both electron beams will be modulatedsimultaneously by the video input signal. of the horizontal deflectionplates, when the electron beam in neck portion is is swept clock wise,as viewed in Figure 3, the electron beam in neck portion It will also beswept clockwise, and vice versa. When the beam from the electron gun inneck portion 24 moves from the right side of the screen to the leftside, its intensity becomes attenuated due to the increased length oftravel thereof. However, the length of travel of the electron beam fromthe electron gun in neck portion i3 is simultaneously being shortened,so that its intensity increases. The result of this arrangement is tomaintain the net excitation of the fluorescent screen I! substantiallyconstant over its entire width, all other factors being equal.

Due to the use of two electron beams to excite the screen rather than asingle beam as in conventional television tubes, the required value ofsecond anode voltage to obtain a given, highlight brightness ismaterially reduced. Also, due to the symmetrical, angled relationship ofthe neck portions to the central light-generating portion of the tube,the over-all, front-to-rear dimension of the tube is substantiallysmaller than the length of a tube giving comparable performance andutilizing a single, axially arranged electron gun, and, therefore, theproblem of designing a suitable cabinet for the television receiver isgreatly simplified.

Where the tube is to be employed for projection television, the lens 33may be either detachable from or may be molded integrally with the rearwall of the central portion of the tube.

The negative ring 29 acts to repel electrons toward the portion of thetube adjacent the fluorescent screen H. The electrostatic field providedby ring 29 thereby assists the field provided by second anode HS inurging the electrons toward the screen ll, thereby improving the clarityof the reproduced image.

By connecting the respective modulating grids 2!, 2i to different signalsources, it is possible to obtain a composite image consisting of afirst picture with a second picture superimposed thereon. By employingthe tube in this manner, it is possible to accurately compare twodifierent signal frequencies by applyin one of the frequengi'es to grid21 and the other frequency to grid Referring now to Figure 4, anotherform of the present invention is disclosed wherein the tube is of theelectromagnetic deflection type. The various elements of the tube aresubstantially the same as in the embodiment of Figures 1 to 3, exceptthat horizontal deflecting coils 36, 37 and 36, 37' are employed withthe left and right" tube neck portions l3 and i l in place of thehorizontal deflection plates of Figures 1 to 3,

Because of the above-describedconnections: I

all)

4.- and vertical deflecting coils, shown at 38 and 38 are employed inplace of the vertical deflection plates of Figures 1 to 3. As shown inFigure 4, the outer terminal of the lower, left, horizontal deflectioncoil 36 and the outer terminal of the upper, right, horizontaldeflection coil 3? are both connected to one output terminal of thehorizontal sweep generator 39, and the outer terminal of the upper, leftcoil 31 and the outer terminal of the lower, right coil 36 are connectedtogether to the other output terminal of said horizontal sweepgenerator. Coils 3E, 37 are woundin the same direction as coils 36',3'5, as viewed in Figure 4, but the magnetomotive forces developed inthe respective sets oi coils 36, 3i and 36, 3'! will be opposite inpolarity due to the above-described manner of connecting the coils tothe horizontal sweep generator. The vertical deflecting coils 38 and 33'are connected in parallel to the output terminals of the vertical sweepgenerator lfi, .as shown in Figure 4. The'operation of the tube 10fFigure 4 will be substantially similar to the operation of the tube ofFigures 1 to 3.

In the embodiment of the invention shown in Figure 5, the left neckportion I3 is provided with electrostatic deflection plates 24, 25,26,121 and the right neck portion it is provided with electromagneticdeflection coils 36, 3?, 38'. The left horizontal deflection plates 2d,25 are connected to the output of a suitable horizontal sweep generator,not shown, and the right, horizontal deflection 00115.36, 31" areconnected. to the output of another'suitable horizontal sweep generator,the respective sweep voltages applied to the plates 24, 25 and the coils36, 37' being out of phase, so that respective electron beams producedby the leftand right electron guns may trace synchronously over thefluorescent screen in the same manner as in the tubes of Figures 1 to 3and Figure 4. The vertical plates 26, 27 and the vertical deflectioncoil 38 are connected to respectivevertical sweep generators whoseoutput voltages are in phase, so that vertical deflections of therespective electron beams are synchronized.

The tube disclosed in Figure 5 is particularly suitable for comparingtwo different signals by applying the respective signals to therespective grid 2i and 2 I In the embodiment of the inventionillustrated in Figure 6, annular, accelerating coils 4| and 42 aremounted externally adjacent the margins of the respective front and rearfaces of the central portion i2 of the tube, the coils being arranged toprovide a magnetornotive force directed axially of said central portionand acting to urge the electron beams toward the fluorescent screen. Thecoils H and 42 may be connected to a constant D.'C. source so as tomerely reinforce the effect of the second anode in attracting electronstoward the screen, or' alternatively may be coupled to the output of thelast video output stage, so as to modulate the elecron beams with thevideo signal. By the use of the accelerating coils, the required secondanode voltage is materially reduced. When the coils d! and 42 arecoupled to the video signal, not only is the picture intensityincreased, but the defocusing of the beams at the side marginal portionsof the screen is reduced. When the coils M and d2 are employed in thelatter manner, they are preferably energized with a steady D. (3.current and the video signal is superimposed thereon.

- of the electromagnetic deflection type of Figure 4. In the illustratedtube of Figure 6, the neck portions I3 and I4 have electromagneticdeflection yokes 44 and 44' mounted thereon which contain theelectromagnetic sweep coils of Figure 4.

A tube similar to that described above and illustrated in any one ofFigures 1 to 6 may be employed in a system such as is described in theMYE Technical Manual, page 280, published by the P. R. Mallory Co., Inc.In this system, a crystal plate is employed in place of the fluorescentscreen and a transparent collector screen is disposed adjacent thecrystal plate. The electron beams are scanned over the collector screenand develop potentials thereon. A projection lamp, a condenser lens anda polarizing element are arranged behind the tube, oriented to projectpolarized light through the crystal plate. Disposed adjacent the frontface of the tube is another polarizing element crossed with respect tothe polarizing system in the tube. Disposed forwardly of the secondpolarizing element is a projection lens arranged to project light fromthe second polarizing element onto a suitable viewing screen. Thepotentials on the collector screen locally rotate the plane ofpolarization of the crystal plate to degrees corresponding to themagnitudes of the local potentials. The intensity of the light emergingfrom the second polarizing element at any point therefore depends uponthe intensity of the electron beams at their corresponding point ofimpingement on the collector screen.

While certain specific embodiments of an im: proved multiple-gun cathoderay tube have been disclosed in the foregoing description, it will beunderstood that various modifications within the spirit of the inventionmay occur to those skilled in the art. Therefore, it is intended that nolimitations be placed on the invention except as defined by the scope ofthe appended claims.

What is claimed is.

1. An electronic picture tube comprising an evacuated envelope having atransparent face internally coated with fluorescent material, a pair ofelectron gun assemblies carried in said envelope, each electron gunassembly being directed toward said transparent face, said electron gunassemblies being disposed on opposite sides of the longitudinal centralaxis of said envelope and having their axes positioned at equal angleswith respect to said longitudinal central axis, respective vertical andhorizontal beam deflection means associated with the electron gunassemblies, the vertical beam deflection means of the respectiveelectron gun assemblies being connected in phase and the horizontal beamdeflection means being connected 180 out of phase, a first conductiveelement mounted adjacent to and surrounding said face, and a secondconductive element mounted in the envelope opposite and spaced from saidface.

2. An electronic picture tube comprising an evacuated envelope having atransparent face internally coated with fluorescent material, a

pair of electron gun assemblies carried in said envelope, each electrongun assembly being directed toward said transparent face, said electrongun assemblies being disposed on opposite sides of the longitudinalcentral axis of said envelope and having their axes positioned at equalangles with respect to said longitudinal central axis, respectivevertical and horizontal beam deflection means associated with theelectron gun assemblies, the vertical beam deflection means of therespective electron gun assemblies being connected in phase and thehorizontal beam deflection means being connected 180 out of phase, aconductive element mounted adjacent to and surrounding said face, and afiat, annular conductive ring mounted in the envelope opposite andspaced from said face between the axes of the electron gun assemblies.

3. An electronic picture tube comprising an evacuated envelope having atransparent face internally coated with fluorescent material, a

pair of electron gun assemblies carried in said envelope, each electrongun assembl being directed toward said transparent face, said electrongun assemblies being disposed on opposite sides of the longitudinalcentral axis of said envelope and having their axes positioned at equalangles with respect to said longitudinal central axis, respectivevertical and horizontal beam deflection means associated with theelectron gun assemblies, the vertical beam deflection means of therespective electron gun assemblies being connected in phase and thehorizontal beam deflection means being connected 180 out of phase, aconductive element mounted adjacent to and surrounding said face, theenvelope wall opposite said face being transparent, and a flat angularconductive ring mounted on said opposite envelope wall.

4. An electronic picture tube comprising an evacuated envelope having atransparent face internally coated with fluorescent material, a pair ofelectron gun assemblies carried in said envelope, each electron gunassembly being directed toward said transparent face, said electron gunassemblies being disposed on opposite sides of the longitudinal centralaxis of said envelope and having their axes positioned at equal angleswith respect to said longitudinal central axis, respective vertical andhorizontal beam deflection means associated with the electron gunassemblies, the vertical beam deflection means of the respectiveelectron gun assemblies being connected in phase and the horizontal beamdeflection means being connected 180 out of phase, a conductive elementmounted adjacent to and surrounding said face, and a transparent lenscarried by the envelope opposite said face.

5. An electronic picture tube comprising an evacuated envelope having atransparent face internally coated with fluorescent material, a pair .ofelectron gun assemblies carried in said envelope, each electron gunassembly being directed toward said transparent face, said electron gunassemblies being disposed on opposite sides of the longitudinal centralaxis of said envelope and having their axes positioned at equal angleswith respect to said longitudinal central axis, respective vertical andhorizontal beam deflection means associated with the electron gunassemblies, the vertical beam deflection means of the respectiveelectron gun assemblies being connected in phase and the horizontal beamdeflection means being connected 180 out of '7 phase, and a transparentlens carried by the envelope wall opposite said face. V

6. An electronic picture tube comprising an evacuated envelope having atransparent face internally coated with fluorescent material, a pair ofelectron gun assemblies carried in said envelope, each electron gunassembly being directed toward said transparent face, said electron gunassemblies being disposed on opposite sides of the longitudinal centralaxis of said envelope and having their axes positioned at equal angleswith respect to said longitudinal central axis, respective vertical andhorizontal beam deflection means associated with the electron gunassemblies, the vertical beam deflection means of the respectiveelectron gun assemblies being connected in phase and the horizontal beamdeflection means being connected 180 out of phase, a conductive elementmounted adjacent to and surrounding said face, a transparent lenscarried by the envelope wall opposite said face, and a, flat annularconductive ring mounted on said opposite envelope wall around theperiphery of said lens.

7. An electronic picture tube comprising an evacuated envelope having atransparent face internally coated with fluorescent material, a pair ofelectron gun assemblies carried in said envelope, each electron gunassembly being directed toward said transparent face, said electron gunassemblies being disposed on opposite sides of the longitudinal centralaxis of said envelope and having their axes positioned at equal angleswith respect to said longitudinal central axis, respective vertical andhorizontal beam deflection means associated with the electron gunassemblies, the vertical beam deflection means of the respectiveelectron gun assemblies being connected in phase and the horizontal beamdeflection means being connected 180 out of phase, and an acceleratingcoil mounted concentrically with said face, the axis of said coil being8 included between the axes .of the electron gun assemblies.

8. An electronic picture tube comprising an evacuated envelope having atransparent face internally coated with fluorescent material, a pair ofelectron gun assemblies carried in said envelope, each electron gunassembly being directed toward said transparent face, said electron gunassemblies being disposed on opposite sides of the longitudinal centralaxis of said envelope and having their axes positioned at equal angleswith respect to said longitudinal central axis; respective vertical andhorizontal beam deflection means associated with the electron gunassemblies, the vertical beam deflection means of the respectiveelectron gun assemblies being connected in phase and the horizontal beamdeflection means being connected out of phase, a first conductiveelement mounted adjacent to and surrounding said face, a secondconductive element mounted in the envelope opposite and spaced from saidface, and an accelerating coil mounted concentricall with said face, theaxis of said coil being included between the axes of the electron gunassemblies.

JOSE W. ACOSTA.

REFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 2,147,760 Vance et al Feb. 21,1939 2,179,205 Toulon Nov. 7, 1939 2,227,484 Bouwers Jan. 7, 19412,260,911 Knick et al. Oct. 28, 1941 2,402,758 Leverenz June 25, 19462,412,520 Langmuir et a1 Dec. 10, 1946 2,457,175 Parker Dec. 28, 19482,464,420 Snyder Mar. 15, 1949 2,481,458 Wertz Sept. 6, 1949 2,481,839Goldsmith Sept. 13, 1949

